Aluminum alloys having silicon, magnesium, copper and zinc

ABSTRACT

New aluminum alloys are disclosed. The new aluminum alloys may include from 0.70 to 1.4 wt. % Si, from 0.70 to 1.3 wt. % Mg, wherein (wt. % Mg)/(wt. % Si) is not greater than 1.40, from 0.70 - 3.0 wt. % Zn, from 0.55 to 1.3 wt. % Cu, wherein the total amount of Si+Mg+Zn+Cu is not greater than 4.25 wt. %, from 0.01 to 0.30 wt. % Fe, up to 0.70 wt. % Mn, up to 0.15 wt. % Cr, up to 0.20 wt. % Zr, up to 0.20 wt. % V, and up to 0.25 wt. % Ti, the balance being aluminum, optional incidental elements and impurities. The new aluminum alloys may realize an improved combination of properties, such as an improved combination of strength, formability and/or corrosion resistance.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Patent App. No. PCT/US2020/033806, filed May 20, 2020, which claims benefit of priority of U.S. Patent Application No. 62/858,209, filed Jun. 6, 2019, entitled “ALUMINUM ALLOYS HAVING SILICON, MAGNESIUM, COPPER AND ZINC”, each of which is incorporated herein by reference in its entirety.

BACKGROUND

6xxx aluminum alloys are aluminum alloys having silicon and magnesium to produce the precipitate magnesium silicide (Mg₂Si). The alloy 6061 has been used in various applications for several decades. However, improving one or more properties of an aluminum alloy without degrading other properties is elusive. For automotive applications, a sheet having good formability prior to thermal treatment but with high strength after thermal treatment would be useful.

SUMMARY OF THE DISCLOSURE

Broadly, the present patent application relates to new aluminum alloys and methods for making the same. The new aluminum alloys generally include from 0.70 to 1.4 wt. % Si, from 0.70 to 1.3 wt. % Mg, wherein (wt. % Mg)/(wt. % Si) is not greater than 1.40, from 0.70 to 3.0 wt. % Zn, from 0.55 to 1.3 wt. % Cu, wherein the total amount of Si+Mg+Zn+Cu is not greater than 4.25 wt. %, from 0.01 to 0.30 wt. % Fe, up to 0.70 wt. % Mn, up to 0.15 wt. % Cr, up to 0.20 wt. % Zr, up to 0.20 wt. % V, and up to 0.25 wt. % Ti, the balance being aluminum, optional incidental elements and impurities. The new aluminum alloys may realize an improved combination of properties, such as an improved combination of two or more of naturally aged strength, paint bake strength, T6 strength, formability, ductility, and corrosion resistance. The new aluminum alloys may be used in a variety of applications, such as in automotive applications (e.g., as a sheet product).

i. Composition

As noted above, the new aluminum alloys generally comprises (and in some instances consist essentially of, or consist of) from 0.70 to 1.4 wt. % Si, from 0.70 to 1.3 wt. % Mg, wherein (wt. % Mg)/(wt. % Si) is not greater than 1.40, from 0.70 to 3.0 wt. % Zn, from 0.55 to 1.3 wt. % Cu, wherein the total amount of Si+Mg+Zn+Cu is not greater than 4.25 wt. %, from 0.01 to 0.30 wt. % Fe, up to 0.70 wt. % Mn, up to 0.15 wt. % Cr, up to 0.20 wt. % Zr, up to 0.20 wt. % V, and up to 0.25 wt. % Ti, the balance being aluminum, optional incidental elements and impurities. Using these specific amounts of elements may result in unique and useful products for use in, for instance, automotive applications, where good formability prior to thermal treatment is required, high strength after thermal treatment is also required.

As noted above, the new aluminum alloys generally include from 0.70 to 1.4 wt. % Si. Silicon may facilitate strength. As shown by the below examples, use of silicon outside this range may be detrimental. In one embodiment, a new aluminum alloy includes at least 0.75 wt. % Si. In another embodiment, a new aluminum alloy includes at least 0.80 wt. % Si. In yet another embodiment, a new aluminum alloy includes at least 0.85 wt. % Si. In one embodiment, a new aluminum alloy includes not greater than 1.35 wt. % Si. In another embodiment, a new aluminum alloy includes not greater than 1.30 wt. % Si. In yet another embodiment, a new aluminum alloy includes not greater than 1.25 wt. % Si. In another embodiment, a new aluminum alloy includes not greater than 1.20 wt. % Si. In yet another embodiment, a new aluminum alloy includes not greater than 1.15 wt. % Si. In another embodiment, a new aluminum alloy includes not greater than 1.10 wt. % Si. In yet another embodiment, a new aluminum alloy includes not greater than 1.05 wt. % Si.

As noted above, the new aluminum alloys generally include from 0.70 to 1.3 wt. % Mg. Magnesium may facilitate strength. As shown by the below examples, use of magnesium outside this range may be detrimental. In one embodiment, a new aluminum alloy includes at least 0.75 wt. % Mg. In another embodiment, a new aluminum alloy includes at least 0.80 wt. % Mg. In one embodiment, a new aluminum alloy includes not greater than 1.25 wt. % Mg. In another embodiment, a new aluminum alloy includes not greater than 1.20 wt. % Mg. In yet another embodiment, a new aluminum alloy includes not greater than 1.15 wt. % Mg. In another embodiment, a new aluminum alloy includes not greater than 1.10 wt. % Mg. In yet another embodiment, a new aluminum alloy includes not greater than 1.05 wt. % Mg.

As noted above, the weight ratio of Mg: Si is generally not greater than 1.4:1. The appropriate Mg:Si ratio may facilitate corrosion resistance at applicable strength levels. As shown by the below examples, use of a Mg:Si ratio outside this range may be detrimental. In one embodiment, a weight ratio of Mg: Si is not greater than 1.3:1. In another embodiment, a weight ratio of Mg: Si is not greater than 1.2:1. In one embodiment, a weight ratio of Mg: Si is at least 0.7:1. In another embodiment, a weight ratio of Mg:Si is at least 0.8:1. In yet another embodiment, a weight ratio of Mg:Si is at least 0.9:1.

As noted above, the new aluminum alloys generally include from 0.70 to 3.0 wt. % Zn. Zinc may facilitate strength and the appropriate natural aging response. As shown by the below examples, use of zinc outside this range may be detrimental. In one embodiment, a new aluminum alloy includes at least 0.75 wt. % Zn. In another embodiment, a new aluminum alloy includes at least 0.85 wt. % Zn. In yet another embodiment, a new aluminum alloy includes at least 0.95 wt. % Zn. In another embodiment, a new aluminum alloy includes at least 1.0 wt. % Zn. In yet another embodiment, a new aluminum alloy includes at least 1.05 wt. % Zn. In one embodiment, a new aluminum alloy includes not greater than 2.8 wt. % Zn. In another embodiment, a new aluminum alloy includes not greater than 2.6 wt. % Zn. In yet another embodiment, a new aluminum alloy includes not greater than 2.4 wt. % Zn. In another embodiment, a new aluminum alloy includes not greater than 2.2 wt. % Zn. In yet another embodiment, a new aluminum alloy includes not greater than 2.0 wt. % Zn. In another embodiment, a new aluminum alloy includes not greater than 1.8 wt. % Zn.

As noted above, the new aluminum alloys generally include from 0.55 to 1.3 wt. % Cu. Copper may facilitate strength, corrosion resistance and natural aging response. As shown by the below examples, use of copper outside this range may be detrimental. In one embodiment, a new aluminum alloy includes at least 0.60 wt. % Cu. In another embodiment, a new aluminum alloy includes at least 0.65 wt. % Cu. In yet another embodiment, a new aluminum alloy includes at least 0.70 wt. % Cu. In one embodiment, a new aluminum alloy includes not greater than 1.25 wt. % Cu. In another embodiment, a new aluminum alloy includes not greater than 1.20 wt. % Cu. In yet another embodiment, a new aluminum alloy includes not greater than 1.15 wt. % Cu. In another embodiment, a new aluminum alloy includes not greater than 1.10 wt. % Cu. In yet another embodiment, a new aluminum alloy includes not greater than 1.05 wt. % Cu.

As noted above solute in the alloy is limited, wherein the total amount of Si+Mg+Zn+Cu is not greater than 4.25 wt. %. As shown by the below examples, use of too much solute may be detrimental. Thus, the stated limit.

As noted above, the new aluminum alloys generally include from 0.01 to 0.30 wt. % Fe. Iron may facilitate a proper grain structure and using more than 0.10 wt. % Fe iron may be cost effective. Use of iron outside this range may be cost ineffective and/or detrimental. The amount of iron in the alloy should be restricted such that large primary particles are avoided/restricted/limited during production of aluminum alloy products. In one embodiment, a new aluminum alloy includes at least 0.05 wt. % Fe. In another embodiment, a new aluminum alloy includes at least 0.10 wt. % Fe. In yet another embodiment, a new aluminum alloy includes at least 0.12 wt. % Fe. In one embodiment, a new aluminum alloy includes not greater than 0.25 wt. % Fe. In another embodiment, a new aluminum alloy includes not greater than 0.22 wt. % Fe. In yet another embodiment, a new aluminum alloy includes not greater than 0.19 wt. % Fe. In another embodiment, a new aluminum alloy includes not greater than 0.16 wt. % Fe.

As noted above, the new aluminum alloys may include up to 0.70 wt. % Mn. Manganese may facilitate the proper grain structure. Use of manganese outside this range may be detrimental. The amount of manganese in the alloy should be restricted such that large primary particles are avoided/restricted/limited during production of aluminum alloy products. In one embodiment, a new aluminum alloy includes at least 0.05 wt. % Mn. In another embodiment, a new aluminum alloy includes at least 0.10 wt. % Mn. In yet another embodiment, a new aluminum alloy includes at least 0.15 wt. % Mn. In one embodiment, a new aluminum alloy includes not greater than 0.60 wt. % Mn. In another embodiment, a new aluminum alloy includes not greater than 0.50 wt. % Mn. In yet another embodiment, a new aluminum alloy includes not greater than 0.45 wt. % Mn. In another embodiment, a new aluminum alloy includes not greater than 0.40 wt. % Mn.

As noted above, the new aluminum alloys include not greater than 0.15 wt. % Cr. Using more than 0.15 wt. % chromium may be detrimental to the grain structure and may causes issues with alloy recyclability. In one embodiment, a new aluminum alloy includes not greater than 0.12 wt. % Cr. In another embodiment, a new aluminum alloy includes not greater than 0.10 wt. % Cr. In yet another embodiment, a new aluminum alloy includes not greater than 0.08 wt. % Cr. In another embodiment, a new aluminum alloy includes not greater than 0.06 wt. % Cr. In yet another embodiment, a new aluminum alloy includes not greater than 0.04 wt. % Cr. In another embodiment, a new aluminum alloy includes not greater than 0.03 wt. % Cr. In yet another embodiment, a new aluminum alloy includes not greater than 0.02 wt. % Cr. In another embodiment, a new aluminum alloy includes not greater than 0.01 wt. % Cr.

As noted above, the new aluminum alloys include not greater than 0.20 wt. % Zr. Zirconium is less preferred than manganese for grain structure control, but still may be useful. The amount of zirconium in the alloy should be restricted such that large primary particles are avoided/restricted/limited during production of aluminum alloy products. In one embodiment, a new aluminum alloy includes not greater than 0.15 wt. % Zr. In another embodiment, a new aluminum alloy includes not greater than 0.10 wt. % Zr. In yet another embodiment, a new aluminum alloy includes not greater than 0.08 wt. % Zr. In another embodiment, a new aluminum alloy includes not greater than 0.03 wt. % Zr. In yet another embodiment, a new aluminum alloy includes not greater than 0.01 wt. % Zr. In one embodiment, a new aluminum alloy includes at least 0.01 wt. % Zr (e.g., when Zr is added/used to the alloy for grain structure control.) In another embodiment, a new aluminum alloy includes at least 0.05 wt. % Zr. In one embodiment, a new aluminum alloy includes from 0.07 to 0.15 wt. % Zr.

As noted above, the new aluminum alloys include not greater than 0.20 wt. % V. Vanadium is less preferred than manganese for grain structure control, but still may be useful. The amount of vanadium in the alloy should be restricted such that large primary particles are avoided/restricted/limited during production of aluminum alloy products. In one embodiment, a new aluminum alloy includes not greater than 0.15 wt. % V. In another embodiment, a new aluminum alloy includes not greater than 0.10 wt. % V. In yet another embodiment, a new aluminum alloy includes not greater than 0.08 wt. % V. In another embodiment, a new aluminum alloy includes not greater than 0.03 wt. % V. In yet another embodiment, a new aluminum alloy includes not greater than 0.01 wt. % V. In one embodiment, a new aluminum alloy includes at least 0.01 wt. % V (e.g., when V is added/used to the alloy for grain structure control.) In another embodiment, a new aluminum alloy includes at least 0.05 wt. % V. In one embodiment, a new aluminum alloy includes from 0.07 to 0.15 wt. % V.

As noted above, the new aluminum alloys include not greater than 0.25 wt. % Ti. Titanium may be used during casting for grain refinement. Higher levels of titanium may also facilitate corrosion resistance. The amount of titanium in the alloy should be restricted such that large primary particles are avoided/restricted/limited during production of alloy products. In one embodiment, a new aluminum alloy includes at least 0.005 wt. % Ti. In another embodiment, a new aluminum alloy includes at least 0.01 wt. %Ti. In yet another embodiment, a new aluminum alloy includes at least 0.02 wt. %Ti. In yet another embodiment, a new aluminum alloy includes at least 0.05 wt. % Ti. In one embodiment, a new a new aluminum alloy includes not greater than 0.20 wt. %Ti. In another embodiment, a new a new aluminum alloy includes not greater than 0.15 wt. %Ti. In another embodiment, a new aluminum alloy includes not greater than 0.12 wt. % Ti. In yet another embodiment, a new a new aluminum alloy includes not greater than 0.10 wt. %Ti. In another embodiment, a new a new aluminum alloy includes not greater than 0.08 wt. %Ti. In yet another embodiment, a new a new aluminum alloy includes not greater than 0.05 wt. %Ti. In another embodiment, a new a new aluminum alloy includes not greater than 0.03 wt. %Ti. In one embodiment, a new a new aluminum alloy includes from 0.005 to 0.10 wt. % Ti. In another embodiment, a new aluminum alloy includes from 0.01 to 0.05 wt. % Ti. In yet another embodiment, a new aluminum alloy includes from 0.01 to 0.03 wt. % Ti. The titanium may be in elemental form or in the form of compounds (e.g., TiB₂ or TiC).

As noted above, the balance of the aluminum alloys is generally aluminum, optional incidental elements and impurities. As used herein, “incidental elements” means those elements or materials, other than the above listed elements, that may optionally be added to the alloy to assist in the production of the alloy. Examples of incidental elements include casting aids, such as grain refiners and deoxidizers. Optional incidental elements may be included in the alloy in a cumulative amount of up to 1.0 wt. %. As one non-limiting example, one or more incidental elements may be added to the alloy during casting to reduce or restrict (and is some instances eliminate) ingot cracking due to, for example, oxide fold, pit and oxide patches. These types of incidental elements are generally referred to herein as deoxidizers. Examples of some deoxidizers include Ca, Sr, and Be. When calcium (Ca) is included in the alloy, it is generally present in an amount of up to about 0.05 wt. %, or up to about 0.03 wt. %. In some embodiments, Ca is included in the alloy in an amount of about 0.001-0.03 wt. % or about 0.05 wt. %, such as 0.001-0.008 wt. % (or 10 to 80 ppm). Strontium (Sr) may be included in the alloy as a substitute for Ca (in whole or in part), and thus may be included in the alloy in the same or similar amounts as Ca. Traditionally, beryllium (Be) additions have helped to reduce the tendency of ingot cracking, though for environmental, health and safety reasons, some embodiments of the alloy are substantially Be-free. When Be is included in the alloy, it is generally present in an amount of up to about 20 ppm. Incidental elements may be present in minor amounts, or may be present in significant amounts, and may add desirable or other characteristics on their own without departing from the alloy described herein, so long as the alloy retains the desirable characteristics described herein. It is to be understood, however, that the scope of this disclosure should not/cannot be avoided through the mere addition of an element or elements in quantities that would not otherwise impact on the combinations of properties desired and attained herein.

The new aluminum alloys may contain low amounts of impurities. In one embodiment, a new aluminum alloy includes not greater than 0.15 wt. %, in total, of the impurities, and wherein the new aluminum alloy includes not greater than 0.05 wt. % of each of the impurities. In another embodiment, a new aluminum alloy includes not greater than 0.10 wt. %, in total, of the impurities, and wherein the new aluminum alloy includes not greater than 0.03 wt. % of each of the impurities.

ii. Processing

The new aluminum alloys may be useful in a variety of product forms, including ingot or billet, wrought product forms (plate, forgings and extrusions), shape castings, additively manufactured products, and powder metallurgy products, for instance. For example, the new aluminum alloys may be processed into a variety of wrought forms, such as in rolled form (sheet, plate), as an extrusion, or as a forging, and in a variety of tempers. In this regard, the new aluminum alloys may be cast (e.g., direct chill cast or continuously cast), and then worked (hot and/or cold worked) into the appropriate product form (sheet, plate, extrusion, or forging). After working, the new aluminum alloys may be processed to one of a T temper, a W temper, or an F temper as per ANSI H35.1 (2009). In one embodiment, a new aluminum alloy is processed to a “T temper” (thermally treated). In this regard, the new aluminum alloys may be processed to any of a T1, T2, T3, T4, T5, T6, T7, T8, T9 or T10 temper as per ANSI H35.1 (2009). In one embodiment, the product is processed to a T43 temper (e.g., as per the below examples). In another embodiment, the product is processed to a T6 temper (e.g., as per the below examples). In other embodiments, a new aluminum alloy is processed to an “W temper” (solution heat treated). In another embodiment, no solution heat treatment is applied after working the aluminum alloy into the appropriate product form, and thus the new aluminum alloys may be processed to an “F temper” (as fabricated).

In one embodiment, a new aluminum alloys is a sheet product. In one embodiment, the sheet product has a thickness of from 1.0 to 4.0 mm. In one embodiment, the sheet product is processed to a T4 temper. In one embodiment, the sheet product is processed to a T43 temper. In one embodiment, the sheet product is processed to a T43 temper and then paint baked (e.g., by heating at 180° C. for 20 minutes). In one embodiment, the sheet product is processed to a T43 temper, then paint baked, and then artificially aged to a T6 temper (e.g., by heating at 180° C. for 8 hours). Such sheet products may be useful in automotive applications, as described in further detail below.

iii. Properties

As noted above, the new aluminum alloys may realize an improved combination of properties. In one embodiment, the new aluminum alloy is a sheet product having a thickness of from 1.0 to 4.0 mm, and this aluminum alloy sheet product realizes at least one of the following properties:

(i) a TYS-LT of not greater than 155 MPa at 7 days of natural aging (“TYS-7NA”);

(ii) a TYS-LT of not greater than 175 MPa at 90 days of natural aging (“TYS-90NA”);

(iii) a (TYS-90NA) minus (TYS-7NA) of not greater than 20 MPa;

(iv) a TYS-LT of at least 235 MPa when naturally aged for 30 days followed by paint baking at 180° C. for 20 minutes;

(v) a TYS-LT of at least 230 MPa when naturally aged for 90 days followed by paint baking at 180° C. for 20 minutes; and

(vi) a TYS-LT of at least 350 MPa when naturally aged for 30 days followed by artificially aging at 180° C. for 8 hours.

In one embodiment, the aluminum alloy sheet product realizes at least two of the above properties (i)-(vi). In another embodiment, the aluminum alloy sheet product realizes at least three of the above properties (i)-(vi). In yet another embodiment, the aluminum alloy sheet product realizes at least four of the above properties (i)-(vi). In another embodiment, the aluminum alloy sheet product realizes at least five of the above properties (i)-(vi). In yet another embodiment, the aluminum alloy sheet product realizes all of the above properties (i)-(vi).

As used herein, “TYS-LT” means the long transverse tensile yield strength (0.2% offset) of a product as measured in accordance with ASTM E8 and B557.

As used herein, “TYS-7NA” means the long transverse tensile yield strength of a product at seven days of natural aging.

As used herein, “TYS-90NA” means the long transverse tensile yield strength of a product at ninety days of natural aging.

As used herein, “paint baking” is the application of heat to the product to cure paints or other polymers thereon. A typically automotive paint bake is heating to 180° C. and then holding at 180° C. for 20 minutes (e.g., in a furnace), followed by air cooling to ambient.

As noted above, a new aluminum alloy sheet product may realize a TYS-LT of not greater than 155 MPa at 7 days of natural aging (i.e., TYS-7NA≤155 MPa). Low strength after natural aging is important to allow for subsequent forming of the material (e.g., into automotive sheet components). In one embodiment, a new aluminum alloy sheet product may realize a TYS-LT of not greater than 150 MPa at 7 days of natural aging (i.e., TYS-7NA≤150 MPa). In another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of not greater than 145 MPa at 7 days of natural aging (i.e., TYS-7NA≤145 MPa).

As noted above, a new aluminum alloy sheet product may realize a TYS-LT of not greater than 175 MPa at 90 days of natural aging (i.e., TYS-90NA≤175 MPa). Low strength after natural aging is important to allow for subsequent forming of the material (e.g., into automotive sheet components). Further, automotive sheet products may lie in inventory for several months, so the natural aging response/strength needs to be/remain low for extended periods of time. In one embodiment, a new aluminum alloy sheet product may realize a TYS-LT of not greater than 170 MPa at 90 days of natural aging (i.e., TYS-90NA≤170 MPa). In another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of not greater than 165 MPa at 90 days of natural aging (i.e., TYS-90NA≤165 MPa). In yet another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of not greater than 160 MPa at 90 days of natural aging (i.e., TYS-90NA≤160 MPa). In another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of not greater than 155 MPa at 90 days of natural aging (i.e., TYS-90NA≤155 MPa).

As noted above, the natural aging response should be low. In one embodiment, a new aluminum alloy sheet product may realize a (TYS-90NA) minus (TYS-7NA) of not greater than 20 MPa. That is, the strength of the sheet product increases by not greater than 20 MPa from 7 days of natural aging to 90 days of natural aging. In another embodiment, a new aluminum alloy sheet product may realize a (TYS-90NA) minus (TYS-7NA) of not greater than 18 MPa. In yet another embodiment, a new aluminum alloy sheet product may realize a (TYS-90NA) minus (TYS-7NA) of not greater than 15 MPa. In another embodiment, a new aluminum alloy sheet product may realize a (TYS-90NA) minus (TYS-7NA) of not greater than 12 MPa. In yet another embodiment, a new aluminum alloy sheet product may realize a (TYS-90NA) minus (TYS-7NA) of not greater than 10 MPa. In another embodiment, a new aluminum alloy sheet product may realize a (TYS-90NA) minus (TYS-7NA) of not greater than 8 MPa.

As noted above, a new aluminum alloy sheet product may realize a TYS-LT of at least 235 MPa when naturally aged for 30 days followed by paint baking at 180° C. for 20 minutes. (The phrase “when naturally aged for 30 days followed by paint baking at 180° C. for 20 minutes” is abbreviated herein as “30 days NA+paint bake.”) Paint baking generally occurs after natural aging and after the product has been formed, so high post-paint baking strength may be important. In one embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 240 MPa 30 days NA+paint bake. In another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 245 MPa 30 days NA+paint bake. In yet another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 250 MPa 30 days NA+paint bake. In another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 255 MPa 30 days NA+paint bake. In yet another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 260 MPa 30 days NA+paint bake. In another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 265 MPa 30 days NA+paint bake. In yet another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 270 MPa 30 days NA+paint bake.

As noted above, a new aluminum alloy sheet product may realize a TYS-LT of at least 230 MPa when naturally aged for 90 days followed by paint baking at 180° C. for 20 minutes. (The phrase “when naturally aged for 90 days followed by paint baking at 180° C. for 20 minutes” is abbreviated herein as “90 days NA+paint bake.”) It may be important for the strength decrease after paint bake to be low (e.g., to ensure the product retains a high strength). In one embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 235 MPa 90 days NA+paint bake. In another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 240 MPa 90 days NA+paint bake. In yet another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 245 MPa 90 days NA+paint bake. In another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 250 MPa 90 days NA+paint bake.

As noted above, a new aluminum alloy sheet product may realize a TYS-LT of at least 350 MPa when naturally aged for 30 days followed by artificial aging at 180° C. for 8 hours. (The phrase “when naturally aged for 30 days followed by artificial aging at 180° C. for 8 hours” is abbreviated herein as “30 days NA+AA.”) In some embodiments, it may be useful to artificially age a product (e.g., a naturally aged product and/or a paint baked product) to increase its strength, and achieving high strength may be important. In one embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 355 MPa 30 days NA+AA . In another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 360 MPa 30 days NA+AA. In yet another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 365 MPa 30 days NA+AA. In another embodiment, a new aluminum alloy sheet product may realize a TYS-LT of at least 370 MPa 30 days NA+AA.

The T6 tempering by artificial aging may be heating for any suitable period(s) of time and at any suitable temperature(s). In one embodiment, the T6 tempering is heating at 180° C. for 8 hours, or a substantially similar aging condition, as shown above. As appreciated by those skilled in the art, aging temperatures and/or times may be adjusted based on well-known aging principles and/or formulas. Thus, those skilled in the art could increase the aging temperature but decrease the aging time, or vice-versa, or only slightly change only one of these parameters, and still achieve the same result as “8 hours of aging at a temperature of 180° C.” The amount of artificial aging practices that could achieve the same result as “8 hours of aging at a temperature of 180° C.” is numerous, and therefore all such substitute aging practices are not listed herein. The use of the phrase “or a substantially equivalent artificial aging temperature and duration” or the phrase “or a substantially equivalent practice” is used to capture all such substitute aging practices. As may be appreciated, these substitute artificial aging steps can occur in one or multiple steps, and at one or multiple temperatures.

A new aluminum alloy sheet may also realize other important properties, such as ductility and corrosion resistance. In one embodiment, a new aluminum alloy sheet product may realize an elongation (4D) of at least 15% in the T43 temper when tested in accordance with ASTM E8 and B557. In another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 18% in the T43 temper. In yet another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 20% in the T43 temper. In another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 22% in the T43 temper. In another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 24% in the T43 temper. In yet another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 26% in the T43 temper. In another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 28% in the T43 temper.

In one embodiment, a new aluminum alloy sheet product may realize an elongation (4D) of at least 10% in the paint baked condition (e.g., T43+paint bake) when tested in accordance with ASTM E8 and B557. In another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 12% in the paint baked condition. In yet another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 14% in the paint baked condition. In another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 16% in the paint baked condition. In yet another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 18% in the paint baked condition. In another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 20% in the paint baked condition.

In one embodiment, a new aluminum alloy sheet product may realize an elongation (4D) of at least 10% in the T6 temper when tested in accordance with ASTM E8 and B557. In another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 11% in the T6 temper. In yet another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 12% in the T6 temper. In another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 13% in the T6 temper. In yet another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 14% in the T6 temper. In another embodiment, a new aluminum alloy sheet product realizes an elongation of at least 15% in the T6 temper.

In one embodiment, a new aluminum alloy sheet product is corrosion resistant. In one embodiment, the corrosion resistance is at least intergranular corrosion resistance. In another embodiment, the corrosion resistance is at least filiform corrosion resistance. In another embodiment, the corrosion resistance is both intergranular corrosion resistance and filiform corrosion resistance. Intergranular corrosion resistance is to be measured in accordance with ASTM G110 (5 specimens). Filiform corrosion resistance is to be measured in accordance with ASTM G85-2, and wherein, after exposing samples for 3 weeks, the longest filiform corrosion resistance perpendicular to each of three separate scribes is to be determined.

As it relates to intergranular corrosion resistance, in one embodiment, a new aluminum alloy sheet product realizes a maximum depth of attack of not greater than 225 micrometers and an average depth of attack of not greater than 150 micrometers.

As it relates to filiform corrosion resistance, in one embodiment, a new aluminum alloy sheet product realizes a maximum track length of not greater than 0.35 inch, and with at least 8 tracks being tested. In another embodiment, a new aluminum alloy sheet product realizes a maximum track length of not greater than 0.30 inch, and with at least 8 tracks being tested.

Due to the unique compositions disclosed herein, and with appropriate processing, a new aluminum alloy product may be crack-free after forming (e.g., when pressed/formed into an automotive component, such as an automotive panel). In one embodiment, a new aluminum alloy product is crack-free after forming (e.g., when pressed/formed into an automotive panel/component), is strong (after paint baking and/or T6 tempering, and as defined above), and as is corrosion resistant.

iv. Product Applications

The new aluminum alloy described herein may be used in a variety of applications, such as an automotive, rail, aerospace, or consumer electronics application. For example, a new aluminum alloy may be formed into an automotive part. Non-limiting examples of automotive parts include automotive bodies and automotive panels. Non-limiting examples of automotive panels may be outer panels, inner panels for use in car doors, car hoods, or car trunks (deck lids), among others. One example of an automotive body product may be a structural component, which may be used in welding together sheet metal components of a car body (e.g., body-in-white). The new aluminum alloys may also be used in other transportation applications, such as light or heavy trucks. Consumer electronic product applications include laptop computer cases, battery cases, among other stamped and formed products.

v. Representative, Non-Limiting Clauses

Below are some non-limiting, representative clauses that define one or more inventions. These clauses are non-limiting examples, and are not intended to restrict, and do not restrict, the inventions disclosed herein to the matters described. Indeed, any of the subject matter described in this specification may be used to define one or more inventions.

Clause 1. A aluminum alloy sheet product comprising:

from 0.70 to 1.4 wt. % Si;

from 0.70 to 1.3 wt. % Mg;

wherein (wt. % Mg)/(wt. % Si) is not greater than 1.4:1;

from 0.70 to 3.0 wt. % Zn;

from 0.55 to 1.3 wt. % Cu;

wherein the total amount of Si+Mg+Zn+Cu is not greater than 4.25 wt. %;

from 0.01 to 0.30 wt. % Fe;

up to 0.70 wt. % Mn;

up to 0.15 wt. % Cr;

up to 0.20 wt. % Zr;

up to 0.20 wt. % V;

up to 0.25 wt. % Ti;

the balance being aluminum, optional incidental elements and impurities;

wherein the aluminum alloy sheet product has a thickness of from 1.0 to 4.0 mm;

wherein the aluminum sheet product realizes at least one of the following properties:

(i) a TYS-LT of not greater than 155 MPa at 7 days of natural aging (“TYS-7NA”);

(ii) a TYS-LT of not greater than 175 MPa at 90 days of natural aging (“TYS-90NA”);

(iii) a (TYS-90NA) minus (TYS-7NA) of not greater than 20 MPa;

(iv) a TYS-LT of at least 235 MPa when naturally aged for 30 days and then paint baked at 180° C. for 20 minutes;

(v) a TYS-LT of at least 230 MPa when naturally aged for 90 days and then paint baked at 180° C. for 20 minutes; and

(vi) a TYS-LT of at least 350 MPa when naturally aged for 30 days and then artificially aged at 180° C. for 8 hours.

Clause 2. The aluminum alloy sheet product of clause 1, wherein the aluminum alloy includes at least 0.75 wt. % Si, or at least 0.80 wt. % Si, or at least 0.85 wt. % Si.

Clause 3. The aluminum alloy sheet product of clauses 1-2, wherein the aluminum alloy includes not greater than 1.35 wt. % Si, or not greater than 1.30 wt. % Si, or not greater than 1.25 wt. % Si, or not greater than 1.20 wt. % Si, or not greater than 1.15 wt. % Si, or not greater than 1.10 wt. % Si, or not greater than 1.05 wt. % Si.

Clause 4. The aluminum alloy sheet product of any of clauses 1-3, wherein the aluminum alloy includes at least 0.75 wt. % Mg, or at least 0.80 wt. % Mg.

Clause 5. The aluminum alloy sheet product of any of clauses 1-4, wherein the aluminum alloy includes not greater than 1.25 wt. % Mg, or not greater than 1.20 wt. % Mg, or not greater than 1.15 wt. % Mg, or not greater than 1.10 wt. % Mg, or not greater than 1.05 wt. % Mg.

Clause 6. The aluminum alloy sheet product of any of clauses 1-5, wherein (wt. % Mg)/(wt. % Si) is not greater than 1.3:1, or not greater than 1.2:1.

Clause 7. The aluminum alloy sheet product of any of clauses 1-6, wherein (wt. % Mg)/(wt. % Si) is at least 0.7:1, or at least 0.8:1, or at least 0.9:1.

Clause 8. The aluminum alloy sheet product of any of clauses 1-7, wherein the aluminum alloy includes at least 0.75 wt. % Zn, or at least 0.85 wt. % Zn, or at least 0.95 wt. % Zn, or at least 1.0 wt. % Zn, or at least 1.05 wt. % Zn.

Clause 9. The aluminum alloy sheet product of any of clauses 1-8, wherein the aluminum alloy includes not greater than 2.8 wt. % Zn, or not greater than 2.6 wt. % Zn, or not greater than 2.4 wt. % Zn, or not greater than 2.2 wt. % Zn, or not greater than 2.0 wt. % Zn, or not greater than 1.8 wt. % Zn.

Clause 10. The aluminum alloy sheet product of any of clauses 1-9, wherein the aluminum alloy includes at least 0.60 wt. % Cu, or at least 0.65 wt. % Cu, or at least 0.70 wt. % Cu.

Clause 11. The aluminum alloy sheet product of any of clauses 1-10, wherein the aluminum alloy includes not greater than 1.25 wt. % Cu, or not greater than 1.20 wt. % Cu, or not greater than 1.15 wt. % Cu, or not greater than 1.10 wt. % Cu, or not greater than 1.05 wt. % Cu.

Clause 12. The aluminum alloy sheet product of any of clauses 1-11, wherein the aluminum alloy includes at least 0.05 wt. % Fe, or at least 0.10 wt. % Fe, or at least 0.12 wt. % Fe.

Clause 13. The aluminum alloy sheet product of any of clauses 1-12, wherein the aluminum alloy includes not greater than 0.25 wt. % Fe, or not greater than 0.22 wt. % Fe, or not greater than 0.19 wt. % Fe, or not greater than 0.16 wt. % Fe.

Clause 14. The aluminum alloy sheet product of any of clauses 1-13, wherein the aluminum alloy includes at least 0.05 wt. % Mn, or at least 0.10 wt. % Mn, or at least 0.15 wt. % Mn.

Clause 15. The aluminum alloy sheet product of any clauses 1-14, wherein the aluminum alloy includes not greater than 0.60 wt. % Mn, or not greater than 0.50 wt. % Mn, or not greater than 0.45 wt. % Mn, or not greater than 0.40 wt. % Mn.

Clause 16. The aluminum alloy sheet product of any of clauses 1-15, wherein the aluminum alloy includes not greater than 0.12 wt. % Cr, or not greater than 0.10 wt. % Cr, or not greater than 0.08 wt. % Cr, or not greater than 0.06 wt. % Cr, or not greater than 0.04 wt. % Cr, or not greater than 0.03 wt. % Cr, or not greater than 0.02 wt. % Cr, or not greater than 0.01 wt. % Cr.

Clause 17. The aluminum alloy sheet product of any of clauses 1-16, wherein the aluminum alloy includes not greater than 0.15 wt. % Zr, or not greater than 0.10 wt. % Zr, or not greater than 0.08 wt. % Zr, or not greater than 0.05 wt. % Zr, or not greater than 0.03 wt. % Zr.

Clause 18. The aluminum alloy sheet product of any of clauses 1-17, wherein the aluminum alloy includes at least 0.01 wt. % Zr.

Clause 19. The aluminum alloy sheet product of any of clauses 1-18, wherein the aluminum alloy includes not greater than 0.15 wt. % V, or not greater than 0.10 wt. % V, or not greater than 0.08 wt. % V, or not greater than 0.05 wt. % V, or not greater than 0.03 wt. % V.

Clause 20. The aluminum alloy sheet product of any of clauses 1-19, wherein the aluminum alloy includes at least 0.01 wt. % V.

Clause 21. The aluminum alloy sheet product of any of clauses 1-20, wherein the aluminum alloy includes not greater than 0.12 wt. % Ti, or not greater than 0.10 wt. % Ti.

Clause 22. The aluminum alloy sheet product of any of clauses 1-21, wherein the aluminum alloy includes at least 0.01 wt. % Ti or at least 0.02 wt. % Ti, or at least 0.05 wt. % Ti.

Clause 23. An automotive sheet product made from the aluminum alloy sheet product of any of clauses 1-22.

Clause 24. The automotive sheet product of clause 23, wherein the automotive sheet product realizes at least two of properties (i)-(vi).

Clause 25. The automotive sheet product of clause 23, wherein the automotive sheet product realizes at least three of properties (i)-(vi).

Clause 26. The automotive sheet product of clause 23, wherein the automotive sheet product realizes at least four of properties (i)-(vi).

Clause 27. The automotive sheet product of clause 23, wherein the automotive sheet product realizes at least five of properties (i)-(vi).

Clause 28. The automotive sheet product of clause 23, wherein the automotive sheet product realizes all of properties (i)-(vi).

Clause 29. The automotive sheet product of any of clauses 23-28, wherein the sheet product realizes property (i), and wherein property (i) is not greater than 155 MPa, or not greater than 150 MPa, or not greater than 145 MPa.

Clause 30. The automotive sheet product of any of clauses 23-29, wherein the sheet product realizes property (ii), and wherein property (ii) is not greater than 175 MPa, or not greater than 170 MPa, or not greater than 165 MPa, or not greater than 160 MPa, or not greater than 155 MPa.

Clause 31. The automotive sheet product of any of clauses 23-30, wherein the sheet product realizes property (iii), and wherein property (iii) is not greater than 20 MPa, or not greater than 18 MPa, or not greater than 15 MPa, or not greater than 12 MPa, or not greater than 10 MPa, or not greater than 8 MPa.

Clause 32. The automotive sheet product of any of clauses 23-31, wherein the sheet product realizes property (iv), and wherein property (iv) is at least 235 MPa, or at least 240 MPa, or at least 250 MPa, or at least 255 MPa, or at least 260 MPa, or at least 265 MPa, or at least 270 MPa.

Clause 33. The automotive sheet product of any of clauses 23-32, wherein the sheet product realizes property (v), and wherein property (v) is at least 230 MPa, or at least 235 MPa, or at least 240 MPa, or at least 245 MPa, or at least 250 MPa.

Clause 34. The automotive sheet product of any of clauses 23-33, wherein the sheet product realizes property (vi), and wherein property (vi) is at least 350 MPa, or at least 355 MPa, or at least 360 MPa, or at least 365 MPa, or at least 370 MPa.

Clause 35. The automotive sheet product of any of clauses 23-34, wherein the sheet product realizes an elongation of at least 15% in the T43 temper, or an elongation of at least 18%, or an elongation of at least 20%, or an elongation of at least 22%, or an elongation of at least 24%, or an elongation of at least 26%, or an elongation of at least 28%.

Clause 36. The automotive sheet product of any of clauses 23-35, wherein the sheet product realizes an elongation of at least 10% after paint baking at 180° C. for 20 minutes, or an elongation of at least 12%, or an elongation of at least 14%, or an elongation of at least 16%, or an elongation of at least 18%, or an elongation of at least 20%.

Clause 37. The automotive sheet product of any of clauses 23-36, wherein the sheet product realizes an elongation of at least 10% after artificial aging at 180° C. for 8 hours, or an elongation of at least 11%, or an elongation of at least 12%, or an elongation of at least 13%, or an elongation of at least 14%, or an elongation of at least 15%.

Clause 38. The automotive sheet product of any of clauses 23-37, wherein the sheet product is resistant to intergranular corrosion.

Clause 39. The automotive sheet product of any of clauses 23-38, wherein the sheet product is resistant to filiform corrosion.

Clause 40. The automotive sheet product of any of clauses 23-37, wherein the sheet product is crack-free.

vi. Miscellaneous

These and other aspects, advantages, and novel features of this new technology are set forth in part in the description that follows and will become apparent to those skilled in the art upon examination of the following description and figures, or may be learned by practicing one or more embodiments of the technology provided for by the present disclosure.

Among those benefits and improvements that have been disclosed, other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying figures. Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely illustrative of the invention that may be embodied in various forms. In addition, each of the examples given in connection with the various embodiments of the invention is intended to be illustrative, and not restrictive.

Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise. The phrases “in one embodiment” and “in some embodiments” as used herein do not necessarily refer to the same embodiment(s), though they may. Furthermore, the phrases “in another embodiment” and “in some other embodiments” as used herein do not necessarily refer to a different embodiment, although they may. Thus, various embodiments of the invention may be readily combined, without departing from the scope or spirit of the invention.

In addition, as used herein, the term “or” is an inclusive “or” operator, and is equivalent to the term “and/or,” unless the context clearly dictates otherwise. The term “based on” is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise. In addition, throughout the specification, the meaning of “a,” “an,” and “the” include plural references, unless the context clearly dictates otherwise. The meaning of “in” includes “in” and “on”, unless the context clearly dictates otherwise.

While a number of embodiments of the present invention have been described, it is understood that these embodiments are illustrative only, and not restrictive, and that many modifications may become apparent to those of ordinary skill in the art. Further still, unless the context clearly requires otherwise, the various steps may be carried out in any desired order, and any applicable steps may be added and/or eliminated.

DETAILED DESCRIPTION EXAMPLE 1

Thirty alloys were cast as 6″×18″ ingots. The compositions of those ingots are provided in Table 1, below.

TABLE 1 Composition of Ex. 1 Alloys (in wt. %)* Si + Mg + Alloy Si Fe Cu Mn Mg Cr Zn Cu + Zn  1 0.11 0.17 0.06 0.20 3.75 0.03 3.62 7.54  2 0.10 0.14 0.05 0.19 4.65 0.04 3.49 8.283  3 0.09 0.14 0.05 0.19 3.69 0.02 4.45 8.281  4 0.10 0.18 0.05 0.21 4.74 0.02 4.48 9.37  5 0.10 0.17 0.05 0.20 4.38 0.02 4.03 8.557  6 0.10 0.17 0.06 0.79 4.31 0.03 3.96 8.429  7 0.20 0.17 0.06 0.20 4.12 0.03 4.06 8.438  8 0.11 0.17 0.06 0.78 4.61 0.03 4.63 9.406  9 0.85 0.12 0.49 0.20 0.81 0.03 0.01 2.161 10 1.10 0.12 0.99 0.17 0.82 0.03 — 2.913 11 1.10 0.12 0.49 0.20 1.05 0.02 0.03 2.672 12 1.10 0.13 0.74 0.20 1.16 0.02 0.04 3.039 13 0.73 0.14 0.75 0.20 0.80 0.03 0.01 2.286 14 0.71 0.15 0.97 0.21 0.94 0.03 0.01 2.626 15 0.68 0.15 0.51 0.20 1.20 0.03 — 2.393 16 0.88 0.16 0.99 0.20 1.19 0.03 — 3.064 17 0.86 0.12 0.22 0.19 1.00 0.03 0.75 2.83 18 0.89 0.15 0.74 0.20 0.95 0.03 0.74 3.32 19 1.13 0.13 0.48 0.21 1.19 0.03 0.78 3.58 20 1.07 0.13 0.52 0.19 0.80 0.03 1.53 3.92 21 0.89 0.14 0.75 0.20 1.02 0.03 0.79 3.45 22 0.87 0.14 0.73 0.40 0.97 0.03 0.76 3.33 23 0.68 0.13 0.48 0.19 0.81 0.03 1.51 3.48 24 0.89 0.13 0.51 0.21 1.20 0.03 1.55 4.15 25 0.70 0.13 0.97 0.20 1.16 0.03 1.55 4.38 26 1.09 0.12 0.99 0.18 1.21 0.03 1.52 4.81 27 0.89 0.12 1.00 0.20 0.81 0.03 1.49 4.19 28 0.90 0.12 0.74 0.21 1.00 0.03 2.59 5.23 29** 0.88 0.12 0.76 0.04 0.93 0.25 0.71 3.28 30 1.06 0.13 0.75 0.05 1.20 0.25 0.74 3.75 *The balance of each alloy was 0.02-0.03 wt. % Ti, aluminum, incidental elements and impurities, where each alloy contained not greater than 0.03 wt. % of any one impurity, and where each alloy contained not greater than 0.10 wt. %, in total, of all impurities. **Alloy 29 is an AA6055-style alloy as per U.S. Pat. No. 6,537,392. The Aluminum Association composition limits on the AA6055 alloy are as follows: 0.6-1.2 wt. % Si, 0.30 (max) wt. % Fe, 0.50-1.0 wt. % Cu, 0.10 (max) wt. % Mn, 0.7-1.1 wt. % Mg, 0.20-0.30 wt. % Cr, 0.55-0.9 wt. % Zn, 0.10 (max) wt. % Ti, 0.05 (max) wt. % impurities, 0.15 (max) wt. %, in total, of the other impurities, balance aluminum. (“International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys,” January 2015, page 10, The Aluminum Association, 1525 Wilson Boulevard, Arlington, VA 22209.) Alloys 18, 21-22 and 27 are invention alloys. Alloys 1-17, 19-20 and 23-26 and 28-30 are non-invention alloys and are highlighted in gray.

After casting, the ingots were homogenized and then rolled to final gauge sheet products. The final gauge sheet products had a thickness of 2 mm. The final gauge sheet products were then solution heat treated, quenched to room temperature, and then re-heated to a pre-aging temperature of 82° C. (179.6° F.), and then subject to a simulated coil cool by holding in a furnace programmed to cool at a prescribed cooling rate (consistent with Newtonian cooling) to bring the alloys to a T43 temper. The natural aging response of the alloys was then evaluated by measuring each alloy's mechanical properties at 7 and 90 days of natural aging (as measured from the time the alloys were quenched after solution heat treatment). The paint bake response of the T43 tempered alloys was also tested by heating to 180° C. for 20 minutes. The artificial aging response of the alloys was also tested by aging the T43 tempered alloy at 180° C. for 8 hours (a T6-type temper). The results of the experiments are provided in Table 2, below, where all indicated values are TYS-LT (tensile yield strength values from the long-transverse direction) and in MPa units, NA=natural aging, PB=paint baked as per above, and T6=artificial aged as per above.

TABLE 2 Mechanical Properties of Example 1 Alloys 7 Days 90 Days (90-7 30 days 90 days 30 days Alloy of NA of NA days NA) post PB post PB post T6 1 212 231 19 N/A N/A N/A 2 230  246*  16* N/A N/A N/A 3 260  270*  10* N/A N/A N/A 4 281  294*  13* N/A N/A N/A 5 239 259 20 N/A N/A N/A 6 268 285 17 N/A N/A N/A 7 235 254 20 N/A N/A N/A 8 288 308 21 N/A N/A N/A 9 131 150 19 231 219 342 10 166 171  5 246 238 349 11 150 162 12 237 229 355 12 150 153  3 244 236 352 13 129 150 21 231 223 342 14 151 155  4 232 232 346 15 132 142 10 224 213 322 16 157 164  7 245 242 365 17 138 163 26 240 222 355 18 147 163 16 252 244 360 19 151 165 14 249 242 357 20 134 157 23 235 225 333 21 151 162 10 249 234 362 22 N/A N/A N/A 268 231 364 23 133 152 19 236 221 341 24 151 166 15 261 243 359 25 150 157  8 225 220 337 26 164 173  9 266 248 363 27 148 160 13 245 240 350 28 157 170 13 261 248 360 29 153 167 15 259 249 364 30 137 163 26 259 237 344 *Values for alloys 2-4 are after 60 days of natural aging.

Natural Aging Properties: As shown, non-invention alloys 1-8, 10, 16, 26, and 28 fail to meet the parameter of a TYS-LT of not greater than 155 MPa at 7 days of natural aging and/or not greater than 175 MPa at 90 days of natural aging. Further, the strength of non-invention alloys 8, 13, 17, 20, and 30 increased too much (more than 20 MPa) between 7 days of natural aging and 90 days of natural aging. Achieving strengths of not greater than 155 MPa at 7 days of natural aging, not greater than 175 MPa at 90 days of natural aging, and with not greater than a 20 MPa increase in strength from 7 days of natural aging to 90 days of natural aging is important for formability purposes.

-   -   Note: Natural aging test data for invention alloy 22 are not         included as the B557 test specimens for this alloy were         inappropriate for other non-relevant reasons. However, based on         additional testing, it is believed that alloy 22 would meet the         requirements of a TYS-LT of not greater than 155 at 7 days of         natural aging, a TYS-LT of not greater than 175 at 90 days of         natural aging, and not greater than a 20 MPa increase in TYS-LT         from 7 to 90 days of natural aging.

Paint Bake Properties: As shown, non-invention alloys 9, 11, 13-15, 17, 20, 23 and 25 realized insufficient post paint baking strengths, having a TYS-LT of less than 235 MPa 30 days after paint baking and/or having a TYS-LT of less than 230 MPa 90 days after paint baking. Low post paint baking strength and loss of strength over time after paint baking is not acceptable for most automotive applications.

Artificial Aging Properties: As shown, non-invention alloys 9-10, 13-15, 20, 23, 25 and 30 all realized insufficient artificial aging strengths, having a TYS-LT of less than 350 MPa after artificial aging. Low artificial aging strength may make the alloys inapplicable for some automotive applications.

Aside from mechanical properties, the corrosion resistance of several alloys was also tested, the results of which are provided in Tables 3-4 below.

TABLE 3 Intergranular Corrosion Results (ASTM G110) Corrosion Depth Measurement (μm) Max. Ave. Alloy 1 2 3 4 5 (μm) (μm) Notes 10 177 97.3 94.2 160.3 133.5 177 132 IG + pitting 10 178.7 168 122.7 98.3 79.8 179 130 IG + pitting 14 111 93.5 70.7 103.9 63 111 88 IG + pitting 14 170.3 150.6 140.2 152.6 142.2 170 151 IG + pitting 22 131.8 149 96.6 118 220.6 221 143 IG + pitting 22 142.4 145.7 145 74.7 85.4 146 119 IG + pitting 23 99.8 145.7 87.8 139 128.3 146 120 IG + pitting 23 162.8 116.6 132.7 138 173.5 174 145 IG + pitting 24 180.2 138.7 121.3 162.8 138.7 180 148 IG + pitting 24 172.9 170.9 159.5 162.8 164.2 173 166 IG + pitting

TABLE 4 Filiform Corrosion Results (ASTM DG85-A2) Maximum Track measurements along the scribe AVG MAX Alloy #tracks/cm 1 2 3 4 5 Length Length Alloy 6 >20 0.78 0.78 0.76 0.76 0.75 0.766 0.78 >20 0.6 0.58 0.6 0.6 0.6 0.596 0.60 >20 0.75 0.7 0.65 0.65 0.7 0.690 0.75 Alloy 7 6 0.49 0.49 0.49 0.48 0.45 0.480 0.49 8 0.60 0.58 0.55 0.53 0.50 0.552 0.60 6 0.52 0.48 0.48 0.48 0.40 0.472 0.52 Alloy 10 4 0.30 0.30 0.26 0.25 0.25 0.272 0.30 5 0.38 0.18 0.22 0.19 0.18 0.230 0.38 5 0.36 0.26 0.24 0.23 0.35 0.288 0.36 Alloy 14 5 0.33 0.27 0.25 0.25 0.25 0.270 0.33 7 0.30 0.30 0.34 0.27 0.27 0.296 0.34 6 0.37 0.30 0.33 0.36 0.28 0.328 0.37 Alloy 22 8 0.29 0.24 0.30 0.22 0.24 0.258 0.30 9 0.30 0.25 0.25 0.25 0.25 0.260 0.30 8 0.30 0.30 0.29 0.26 0.25 0.280 0.30 Alloy 23 7 0.21 0.20 0.20 0.20 0.20 0.202 0.21 6 0.26 0.25 0.25 0.25 0.24 0.250 0.26 8 0.26 0.25 0.24 0.24 0.20 0.238 0.26 Alloy 24 5 0.42 0.38 0.37 0.40 0.35 0.384 0.42 6 0.30 0.25 0.30 0.24 0.23 0.264 0.30 6 0.45 0.42 0.50 0.45 0.40 0.444 0.50

As shown, the intergranular corrosion resistance of the alloys is generally acceptable. However, the filiform corrosion of alloys 6-7, 10, 14 and 24 is too high on a maximum length basis, being greater than 0.30 inch. It is expected alloy 12 would behave similar to alloys 10 and 14 as it relates to filiform corrosion, so alloy 12 is considered a non-invention alloy. It is expected alloy 19 would behave similar to alloy 24 as it relates to filiform corrosion, so alloy 19 is considered a non-invention alloy.

These results indicate a specific combination of alloying elements must be used to achieve a combination of properties that may be important for aluminum alloy sheet products.

Specifically, alloys with too much solute (e.g., alloys 1-8, 25-26, 28) may realize unacceptable strength and/or corrosion resistance. Thus, the amount of Si+Mg+Cu+Zn is limited to not greater than 4.25 wt. %. The specific amounts of silicon and magnesium are also important. Too little silicon (e.g., alloys 15 and 23) results in poor properties. Further, the Mg:Si ratio should be not greater than 1.4 as shown by alloys 15 and 25, whose high Mg:Si ratios were at least partially responsible for their poor strengths. High amounts of both copper and zinc should be used to successfully achieve good strength and corrosion resistance. This is shown by contrasting invention alloys 18, 21-22 and 27 versus various non-invention alloys. Finally, chromium should be avoided, as it negatively impacts potential properties (per alloy 30) and also potentially affects the recyclability of the alloys.

While various embodiments of the present disclosure have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present disclosure. 

What is claimed is:
 1. A aluminum alloy sheet product comprising: from 0.70 to 1.4 wt. % Si; from 0.70 to 1.3 wt. % Mg; wherein (wt. % Mg)/(wt. % Si) is not greater than 1.4:1; from 0.70 to 3.0 wt. % Zn; from 0.55 to 1.3 wt. % Cu; wherein the total amount of Si+Mg+Zn+Cu is not greater than 4.25 wt. %; from 0.01 to 0.30 wt. % Fe; up to 0.70 wt. % Mn; up to 0.15 wt. % Cr; up to 0.20 wt. % Zr; up to 0.20 wt. % V; up to 0.25 wt. % Ti; the balance being aluminum, optional incidental elements and impurities; wherein the aluminum alloy sheet product has a thickness of from 1.0 to 4.0 mm; wherein the aluminum sheet product realizes at least one of the following properties: (i) a TYS-LT of not greater than 155 MPa at 7 days of natural aging (“TYS-7NA”); (ii) a TYS-LT of not greater than 175 MPa at 90 days of natural aging (“TYS-90NA”); (iii) a (TYS-90NA) minus (TYS-7NA) of not greater than 20 MPa; (iv) a TYS-LT of at least 235 MPa when naturally aged for 30 days and then paint baked at 180° C. for 20 minutes; (v) a TYS-LT of at least 230 MPa when naturally aged for 90 days and then paint baked at 180° C. for 20 minutes; and (vi) a TYS-LT of at least 350 MPa when naturally aged for 30 days and then artificially aged at 180° C. for 8 hours.
 2. The aluminum alloy sheet product of claim 1, wherein the aluminum alloy includes at least 0.75 wt. % Si.
 3. The aluminum alloy sheet product of claim 1, wherein the aluminum alloy includes not greater than 1.35 wt. % Si.
 4. The aluminum alloy sheet product of claim 1, wherein the aluminum alloy includes at least 0.75 wt. % Mg.
 5. The aluminum alloy sheet product of claim 1, wherein the aluminum alloy includes not greater than 1.25 wt. % Mg.
 6. The aluminum alloy sheet product of claim 1, wherein (wt. % Mg)/(wt. % Si) is not greater than 1.3:1.
 7. The aluminum alloy sheet product of claim 1, wherein (wt. % Mg)/(wt. % Si) is at least 0.7:1.
 8. The aluminum alloy sheet product of claim 1, wherein the aluminum alloy includes at least 1.0 wt. % Zn.
 9. The aluminum alloy sheet product of claim 1, wherein the aluminum alloy includes not greater than 2.8 wt. % Zn.
 10. The aluminum alloy sheet product of claim 1, wherein the aluminum alloy includes at least 0.60 wt. % Cu.
 11. The aluminum alloy sheet product of claim 1, wherein the aluminum alloy includes not greater than 1.25 wt. % Cu.
 12. The aluminum alloy sheet product of claim 1, wherein the aluminum alloy includes at least 0.05 wt. % Mn.
 13. An automotive sheet product made from the aluminum alloy sheet product of claim
 1. 14. An aluminum alloy sheet product comprising: from 0.85 to 1.05 wt. % Si; from 0.80 to 1.10 wt. % Mg; from 0.70 to 1.8 wt. % Zn; from 0.70 to 1.05 wt. % Cu; wherein the total amount of Si+Mg+Zn+Cu is not greater than 4.25 wt. %; from 0.01 to 0.30 wt. % Fe; up to 0.50 wt. % Mn; up to 0.15 wt. % Cr; up to 0.20 wt. % Zr; up to 0.20 wt. % V; up to 0.25 wt. % Ti; the balance being aluminum, optional incidental elements and impurities; wherein the aluminum alloy sheet product has a thickness of from 1.0 to 4.0 mm. 